Sorption rotor

ABSTRACT

The invention relates to a sorption rotor ( 3 ), which is rotationally mounted, whose face ( 6, 7 ) is provided with an inflow sector ( 6 ) and an out-flow sector ( 7 ), and which passes through said sectors when rotating. The sorption rotor also comprises a material matrix ( 12 ) that forms a honeycomb structure with flow channels ( 15 ) axially passing through the sorption rotor ( 3 ). The aim of the invention is to give the sorption rotor ( 3 ) a good thermal stability and strength, a good thermoshock resistance and a high degree of dimensional stability, whereby, at the same time, the sorption rotor should be able to be produced with a comparatively low economical expense. To this end, the invention provides that the material matrix ( 12 ) of the sorption rotor ( 3 ) is made from cellulose paper and is modified using ceramic materials.

The invention relates to a sorption rotor which is rotatably journalledand whose end faces have an inflow sector and an outflow sector throughwhich the sorption rotor passes upon a rotation thereof and which has amatrix material composed of a honeycomb structure with flow passageswhich are axially through-going with respect to the sorption rotor.

Such sorption rotors can, apart from drying through cooling andcondensation, be used for air dehumidification. They are so configuredthat they remove moisture from the air traversing them. In a separatesector through which the sorption rotor passes during its rotarymovement, the moisture stored therein is driven off with the supply ofheat, whereupon the sorption rotor is regenerated for a new moistureremoval.

Since the sorption rotor has a honeycomb structure, the notinsignificant temperature fluctuations and moisture fluctuations candamage matrix materials forming the honeycomb structure and which formthe storage mass. Such sorption rotors can thus only be used incomparatively narrow temperature ranges and moisture ranges. Thesepredetermined temperatures ranges and moisture ranges for controlledoperations can be maintained in practice only with considerabledifficulty. An operation of such sorption rotors in tropical areas isnot possible.

Furthermore, the matrix material of the sorption rotor operates with alithium chloride solution whereby the surfaces are made hygroscopic andwith which an antibacterial effect can be produced. When such a sorptionrotor operates outside the optimal operating conditions, an effect istriggered whereby the lithium chloride in solid or liquid form isleached from the matrix aterial. This effect creates a stronglycorrosive behavior on structures of the apparatus which are contacted bythe lithium chloride.

The regeneration temperature of the aforedescribed sorption rotors islimited to a maximum of 70° C. so that such sorption rotors cannot beused in industrial dehumidification or can only be used in asurprisingly small number of industrial dehumidification systems.

It is the object of the invention to provide a sorption rotor of thetype described at the outset which, by comparison with the state of theart has a significantly increased thermal stability and strength, ischaracterized by good thermal shock resistance and a high shapestability and which also can be fabricated by a comparatively moreeconomical and inexpensive process.

These objects are achieved in accordance with the invention in that thematrix material of the sorption rotor is composed of cellulose paper andis modified by means of ceramic material. The cellulose paperconstituting the matrix material of the sorption rotor can be modifiedwith ceramic precursors according to the invention that are stable up toa temperature of at least 150° C. and show no shape changes with longterm use under constant temperature fluctuations and moisturefluctuations. Furthermore, the cellulose paper forming the workpiecematerial has a highly porous hygroscopic surface with a defined porestructure. Consequently, the sorption rotor can be fabricated at reducedcost with a high efficiency and a stable structure.

When the conditions of use involve a maximum use temperature up to 150°C., the matrix material constituted of cellulose paper of the sorptionrotor can be made by a so-called sol-gel process with the requisitecharacteristics.

Thus, the matrix material of the sorption rotor comprised of cellulosepaper can be infiltrated with a sol-gel system or a gel-forming lowviscosity liquid which, for example, contains SiO₂, Al₂O₃ and/or TiO₂.

The use of SiO₂ in the sol-gel system gives rise to a high specificsurface area of the cellulose paper forming the matrix material; the useof Al₂O₃ in the sol-gel system has the consequence of importing a highmechanical strength to the matrix material. Through the use of TiO₂ inthe sol-gel system, there is a modification of the SiO₂ and the Al₂O₃systems and in addition, a desired antibacterial effect.

An especially advantageous embodiment of the sorption rotor according tothe invention is attainable when the matrix material constituted from acellulose paper is infiltrated with a gel-forming low viscosity formingliquid or a gel system which apart from the ceramic material containsadsorptively effective solids, preferably zeolites.

After the immersion of the matrix material in the sol-gel system orafter infiltration with this sol-gel system which can be effected atroom temperature and which is selected for each predetermined usepurpose, the matrix material is dried at a temperature between 100° C.and 200° C.

The pH value and the temperature for the infiltration and for the dryingprocess are preferably so selected or adjusted that a high water vaporabsorption is enabled by the defined pore structure which is produced inthe matrix material.

The cellulose fibers forming the cellulose paper are stable up to amaximum of 180° C. and from a temperature of 120° C. show strongcoloration. This basic strength of the cellulose paper is furtherstabilized by the ceramic modification of the ceramic phase as hasalready been indicated. Since, however, the cellulose paper forming thestarting material retains its original shape, it may not be suitable forall desirable temperature ranges and moisture ranges for use as sorptionrotors manufactured and configured as previously described.

A significant broadening of the fields of application of the rotor heatexchanger or the sorption rotors associated there-with according to theinvention is achieved when the matrix material forming the honeycombstructure of the sorption rotor is sintered into a self-supportingcomposite ceramic. This sintering can be carried out at temperaturesabove 800° C., preferably at about 850° C. in air. In this manner withcomparatively low cost and economically, a configuration of the matrixmaterial of the sorption rotor can be produced which is effective fortemperature ranges significantly above 150° C. and whereby hithertounattainable moisture ranges can be covered as well. Such a sorptionrotor is suitable even for industrial purposes over wide ranges.

When the humidity characteristics of the self supporting compositeceramic is still not sufficient for certain fields of use andrequirement profiles, it is possible through a further sintering processto convert the carbon component in the matrix material with silicon toan SiC ceramic. This sintering process is carried out with an inert gastreatment at temperatures above 800° C. With the transformation of theworkpiece material according to the present invention, a completelyceramic character can be obtained which produces the finest pores in thesurface of the matrix material. In case these pores do not enablesufficient moisture absorption for certain applications, it isadvantageous to reinfilitrate the sintered matrix anew with a sol-gelsystem and then to effect a fresh drying.

To produce an antibacterial effect, the embodiments according to theinvention that have been described can coat the matrix material of asorption rotor according to the invention with inhibited lithiumchloride.

Alternatively it is possible, to insure killing of micro-organisms toadd biocidally effective solid substances which can bind to the gelforming low viscosity liquid or the sol-gel system which is infiltratedinto the cellulose paper forming the matrix material. It has been foundto be especially advantageous in this connection to use the solidsubstances Amina T100 and Limago T100 which are substances bearing theregistered trademarks of CREAVIS Gesellschaft für Technologie andInnovation mbH.

The aforedescribed sorption rotor according to the invention can befabricated at low technological cost and hence economically by themethods of patent claims 15 through 25.

In the following the invention is described in greater detail inconnection with an embodiment and with reference to the drawing. Itshows:

FIG. 1 a view of a sorption rotor according to the invention;

FIG. 2 a detail A from FIG. 1.

An air dehumidifying device 1 shown in FIG. 1 in a perspective view hasa generally square frame 2 in the illustrated embodiment.

Within the generally square frame 2, a sorption rotor 3 is rotatablyarranged on a hub 4. A motor 5 serves as the drive for rotating movementof the sorption rotor 3. In an end or flow cross sectional area of thesorption rotor 3, the latter passes into an inflow sector 6 and anoutflow sector 7. In the illustrated embodiment, the inflow sector 6 isconfigured to lie below the horizontal beam 8 which connects the twoopposite sides of the frame 2 with one another. The outflow sector 7 islocated above the horizontal beam 8.

The inflow sector 6 of the air dehumidifying device is traversed by aprocess flow or inflow of air 9. The process temperature or inflowingair temperature is thereby increased. The moisture is stored in thesorption rotor 3 by depositing upon the surface thereof itself. When thesorption rotor 3 traverses the outflow sector 7, the stored moisture isdriven off by the heated regeneration air stream, whereby the sorptionrotor 3 is regenerated.

The sorption rotor 3 is comprised of a matrix material of cellulosepaper whose basic construction is illustrated in FIG. 2 which is adetail A from FIG. 1 of the sorption rotor 3 and from which by contrastwith the illustration in FIG. 1, a precise detailed construction of thesorption rotor 3 can be seen. The matrix material 12 is comprised ofsmooth cylindrical and buckled, corrugated or folded cellulosic paperfoils 13 or 14, whereby each buckled, corrugated or folded cellulosepaper foil 13 is configured with two planar or smooth cylindricalcellulosic paper foils 14 defining flow passages 15 which traverse thesorption rotor 3 or the matrix material 12 thereof in the flowdirection.

The surfaces of the cellulose paper foil 13, 14, have a capillarystructure which is better capable of transferring the air humidity.Furthermore, the flow passages 15 formed by the surfaces of thecellulose paper foils 13, 14 are treated with a lithium chloridesolution which, for example, contains 3 to 13 weight % lithium chloridein ethanol. Inhibited lithium chloride is used as the lithium chlorideand the inhibiting agent can have a basis in a chromatic substance or asmall proportion of lithium nitrate can also be used for inhibition.

Prior to the treatment with the lithium chloride solution, the matrixmaterial 12 comprised of the cellulose paper is modified by means ofceramic materials. They are immersed in or infiltrated with a sol-gelsystem which contains SiO₂ and/or Al₂O₃ and/or TiO₂ and/or mullite. Theinfiltration of the workpiece matrix 12 fabricated from cellulose paperwith the sol-gel system is effected at room temperature. After theinfiltration, the matrix material impregnated with the sol-gel system isdried at a temperature between 100° C. and 200° C.

Furthermore, the sol-gel system or the gel-forming low viscosity liquidcan contain adsorptively effective solids in the form of zeolites whenused for the infiltration of the matrix material of the sorption rotor;to achieve a microbacterial effect, it is possible instead of or inaddition to the use of lithium chloride to add to a sol-gel system or agel-forming low viscosity system liquid which already has the previouslydescribed components a biocidally effective solid capable of bindingfirmly and which may be, for example, Amina T100 and/or Limago T100, thelast mentioned designations being registered marks of CREAVISGesellschaft für Technologie and Innovation mbH.

The pH value and the temperature of the infiltration as well as thedrying stage are so selected and adjusted that the surface of the matrixmaterial comprised of the cellulose paper has a defined pore structurewhich enables a high degree of adsorption of water vapor.

In another embodiment of the sorption rotor 3 according to the inventionthe matrix 12 is sintered to a composite ceramic. With this sintering anincrease in the temperature resistance and moisture resistance of thestructure of the workpiece material 12 of the sorption rotor 3 can beachieved.

The sintering process is carried out at temperatures above 800° C., forexample, a temperature of 850° C. in air.

When the thus achieved strength characteristics of the matrix material12 of the sorption rotor 3 are not sufficient for certain applications,it is possible to carry out the sintering process in two stages wherebythe second stage of the sintering process is carried out at temperaturesabove 800° C. in inert gas whereby the carbon content of the matrixmaterial is reacted with silicon to from SiC ceramic. By means of theone sintering process or the two sintering processes, the matrixmaterial 12 of the sorption rotor 3 is transformed into a full ceramicwhereby in the course of this conversion, extremely fine pores areproduced in the surfaces of the structure 12. For the usualapplications, the fine pores that are thus generated have sufficientwater vapor adsorption. If, in certain cases, this is not satisfactory,the matrix material 12 is subjected to infiltration anew with thepreviously described sol-gel system and is subjected to drying.

1. A sorption rotor (3) which is rotatably journalled and whose endfaces have an inflow sector (6) and an outflow sector (7) through whichthe sorption rotor (3) travels during a revolution and which comprises amatrix material (12) which has a honeycomb structure with axiallythroughgoing flow passages (15), characterized in that the matrixmaterial (12) of the sorption rotor (3) is constituted of cellulosepaper modified by means of ceramic material from a sol-gel system or agel-forming low-viscosity liquid infiltrated into the matrix material.2. The sorption rotor according to claim 1 whose matrix material (12)comprised of cellulose paper is infiltrated with an SiO₂-containingsol-gel system.
 3. The sorption rotor according to claim 1 whose matrixmaterial (12) comprised of cellulose paper is infiltrated with anAl₂O₃-containing sol-gel system.
 4. The sorption rotor according toclaim 1 whose matrix material (12) comprised of cellulose paper isinfiltrated with a TiO₂-containing sol-gel system.
 5. The sorption rotoraccording to claim 1 whose matrix material (12) comprised of cellulosepaper is infiltrated with a gel-forming low-viscosity liquid or asol-gel system to which adsorptively effective solids are added.
 6. Thesorption rotor according to claim 5 in which the adsorptively effectivesolid is a zeolite.
 7. The sorption rotor according to claim 1 whosematrix material (12) infiltrated with the sol-gel system is dried. 8.The sorption rotor according to whose matrix material (12) infiltratedwith the sol-gel system is sintered to a self-supporting compositeceramic.
 9. The sorption rotor according to claim 8 in whoseself-supporting composite ceramic formed by sintering the matrixmaterial (12) has its carbon component reacted with silicon to an SiCceramic.
 10. The sorption rotor according to claim 8 whose matrixmaterial (12) is sintered to a self-supporting ceramic and in which thecarbon component is optionally reacted with silicon to an SiC ceramic inwhich a sol-gel system is reinfiltrated into the composite ceramic andthen again dried.
 11. The sorption rotor according to claim 1 whosematrix material (12) is coated with inhibited lithium chloride.
 12. Thesorption rotor according to claim 1 whose matrix material (12) made fromcellulose paper is infiltrated with a gel-forming low-viscosity liquidor a sol-gel system to which a biocidally effective firmly bindablesolid is added.
 13. The sorption rotor according to claim 12 in whichthe biocidally effective firmly bindable solid is Amina T100 or LimagoT100 (registered marks of Creavis Gesellschaft für Technologie andInnovation mbh).
 14. A method of producing a sorption rotor (3)characterized in that a matrix material (12) of the sorption rotor (3)is made from cellulose paper modified with ceramic material from asol-gel system or a gel-forming low-viscosity liquid infiltrated intothe matrix material.
 15. A method according to claim 14 in which thematrix material (12) of cellulose paper is infiltrated with a sol-gelsystem containing SiO₂ and/or Al₂O₃ and/or TiO₂.
 16. The methodaccording to claim 14 in which the matrix material (12) of cellulosepaper is infiltrated with a gel-forming low-viscosity liquid or asol-gel system to which the adsorptively effective solid or solids,especially a zeolite, is added.
 17. The method according to claim 14 inwhich the matrix material (12) of cellulose paper is infiltrated at roomtemperature with the sol-gel system and is dried at a temperaturebetween 100° and 200° C.
 18. The method according to claim 14 in whichthe pH value and the temperature of the infiltration and drying processare so selected and adjusted that a defined pore structure is producedon the matrix material (12) which enables an increased water vaporadsorption.
 19. The method according to claim 14 in which the matrixmaterial (12) infiltrated with the sol-gel system is sintered to aself-supporting composite ceramic.
 20. The method according to claim 19in which the matrix material (12) infiltrated with the sol-gel system issintered in air at a temperature above 800° C., for example, 850° C. 21.The method according to claim 19 in which the sintered matrix material(12) is sintered at a temperature above 800° C. in an inert gas so thatthe carbon component contained in the matrix material (12) is reactedwith silicon to an SiC ceramic.
 22. The method according to claim 19 inwhich the sintered matrix material (12) is reinfiltrated with a sol-gelsystem and dried again.
 23. The method according to claim 14 in whichthe matrix material (12) of cellulose paper is infiltrated with agel-forming low-viscosity liquid or a sol-gel system to which is added abiocidally effective solids which can be bound firmly, especially AminaT100 or Limago T100 (registered marks of Creavis Gesellschaft fürTechnologie and Innovation mbh).